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Design of Intercepting Sewers
Published in Syed R. Qasim, Wastewater Treatment Plants, 2017
Sewer cleaning is a preventive measure to protect certain lines from stoppages. It can be achieved by the following procedures: Hydraulic flushing is done by attaching hose to fire hydrant or sewer-cleaning machines where high-pressure pumps are used. High-pressure water jet cleans the lines. Care should be taken since high-pressure jet may damage the corroded, cracked, or broken lines. Backing up of sewers should be avoided during flushing operation.Sewer balls are effective means of removing deposits, slime, and grease from the lines. The ball is inserted in the upstream manhole and is pulled downstream by a rope. The ball adjusts itself to the irregularities of the pipe and water held behind the ball rushes around the ball thus flushing grease, slime, and deposits. Roots up to pencil size are broken off and removed.4Greater accumulations are removed by special buckets or scoops. The bucket is pulled down the line until the operator feels that it is full. It is then pulled backwards, removed, and emptied. A bucket does not work well on pipes that are out of line because of differential settlement.
Machinability of Inconel 718: A critical review on the impact of cutting temperatures
Published in Materials and Manufacturing Processes, 2021
Kore Mahesh, Jibin T Philip, S N Joshi, Basil Kuriachen
Kitagawa et al.[40] conducted experiments with limited cooling at the interfaces of tool-workpiece and tool-chip in cutting of Ti-6Al-6 V-2Sn and Inconel 718. Due to the development of high peak temperatures, the coolants rapidly evaporate while machining these alloys. Hence, a steam “blanket” is created and restrict fluid penetration into tool and chip contact zones. In the above context, for improving the efficacy of cutting fluids in terms of channeling its flow to the interaction zones and usage of the fluid jet at high pressures, Pigott and Colwell[103] executed a novel technique in the 1950s, namely, high-pressure jet assistance (HPJA). The above process improved the life expectancy of the tool significantly (eight times). During HPJA a high-pressure wedge is generated at the interaction zones through penetration of fluid jet, thereby aiding the clearance of the chips from the tool. It gives access for coolant to reach the cutting edge. During machining, there are three ways to channel the medium (cutting fluid) into the interaction zone: (a) flow of the medium along the direction of the rake face (Fig. 13(a)), leading to reduced tool wear through controlled friction and breakage of the chips, aided by the reduced heat generation and experienced forces; (b) flow of medium along the direction of the flank face (Fig. 13(b)), the surface finish achieved is better by lowering the flank wear and cutting temperatures at the space between machined and flank surfaces; (c) flow of medium along the direction of the clearance and rake surfaces (Fig. 13(c)). Another way of directing the fluid (Fig. 13(d)) for improvement in chip breaking is through the direct supply of cutting fluid on the chip. It is possible to direct the cutting fluid in four distinct ways. In which, the last method (Fig. 13(d)) is presumably the most suitable method for machining of the high-temperature resistant alloys (Inconel 718). Due to the friction between the chip and the tool interface, heat is generated at the secondary shear zone leading to high cutting temperatures, and rapid tool wear occurs through the diffusion mechanism. By applying these techniques to improve the machining performance of the superalloys by reducing the curl radius of the chip (reduction in the chip-tool contact length), the chips are broken into smaller/shorter segments during cutting. It may lead to a decrease in friction at the secondary shear zone, assisting in lowering the cutting temperatures. But this method can be expensive and requires precise monitoring of the cutting tool during machining than the other three techniques. A slot/hole should be provided on the cutting tool’s body for directing the cutting fluid, thereby increasing the cost of the tool. Besides, there are chances for the vibration of the cutting tool during machining, if not correctly handled.